Integrated Stator Cooling Jacket System

This application is a Continuation application of U.S. Continuation application Ser. No. 18/493,138 filed Oct. 24, 2023; which claims the benefit of an earlier filing date from U.S. Continuation-in-Part application Ser. No. 17/723,618 filed Apr. 19, 2022; which claims the benefit of an earlier filing date from U.S. Non-Provisional patent application Ser. No. 16/739,264 filed Jan. 10, 2020, now U.S. Pat. No. 11,811,294, issued Nov. 7, 2023; which claims the benefit of an earlier filing date from U.S. Provisional Application Ser. No. 62/793,215 filed Jan. 16, 2019, the entire disclosure of which is incorporated herein by reference. This application is also a Continuation of U.S. Non-Provisional application Ser. No. 17/075,768 filed Oct. 21, 2020, now U.S. Pat. No. 12,162,343, issued Dec. 10, 2024; which claims the benefit of U.S. Provisional Application Ser. No. 62/929,844 filed Nov. 2, 2019 and U.S. Provisional Application Ser. No. 62/930,028 filed Nov. 4, 2019; the entire disclosures of which are incorporated herein by reference.

Exemplary embodiments pertain to the art of electric motors and, more particularly, to an electric motor having an integrated stator cooling system.

During operation, electric motors produce heat. Often times, rotating components of an electric motor may support a fan member that directs a flow of air through internal motor components. The flow of air may help with smaller systems, such as alternators, and systems that are installed in in open areas, such as generators. The flow of air is not always sufficient in high output systems, particularly those installed in closed areas, such as motor vehicle engine compartments.

Electric motors that are employed as prime movers in a motor vehicle typically include a liquid coolant system. The electric motor includes a stator formed from a plurality of stator laminations and a rotor. The liquid cooling system may include an inlet that receives coolant and an outlet that guides coolant to a heat exchange system. The coolant may flow in a jacket arranged radially outwardly of a stator of the electric motor. Specifically, the coolant may flow through small openings in the housing down onto end turns of a stator winding. The coolant runs over the end turns and passes to the outlet. Transferring heat from the end turns to the coolant reduces a portion of an overall heat signature of the electric motor. However, the end turns have a relatively small surface area relative to an overall size of the stator thereby limiting cooling efficiency.

Other systems rely on direct contact between an outer surface of the stator and an inner surface of a motor housing. In some cases, a cooling jacket may be defined at the inner surface of the housing. Heat may flow from the stator, through the housing, into the coolant passing through the cooling jacket. Indirect contact between a coolant and a surface to be cooled limits heat transfer capacity. In other systems, the heat may pass from an outer surface of the stator into coolant flowing through the housing. The outer surface of the stator possess a relatively small surface area when considered in relation to an overall area of the stator laminations. Accordingly, the industry would be receptive to electric motor cooling systems that remove heat from a larger surface area of the stator directly into a coolant to increase cooing efficacy.

Disclosed is an electric machine including a housing having an outer surface, an inner surface, an upper portion, and a bottom portion. The bottom portion supports a coolant inlet and a coolant outlet. A stator is mounted in the housing. The stator includes a stator core formed from a plurality of stator laminations, and a stator winding having a first end turn and a second end turn. The plurality of stator laminations includes a coolant flow path having a plurality of coolant channels that extends circumferentially about the stator. A first portion of the plurality of coolant channels direct a coolant circumferentially about the stator in a clockwise direction and a second portion of the plurality of coolant channels direct the coolant circumferentially about the stator in a counter-clockwise direction. The coolant flow path includes a first outlet and a second outlet arranged at the upper portion of the housing. The first outlet directs coolant axially outward of the plurality of stator laminations onto the first end turn, and the second outlet directing coolant axially outward of the plurality of stator laminations onto the second end turn.

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

With initial reference to, an electric motor in accordance with a non-limiting example, is indicated generally at. Electric motorincludes a housinghaving an outer surfaceand an inner surface. Housingalso includes a coolant inletand a coolant outlet. The particular location and orientation of coolant inletand coolant outletmay vary. Electric motorincludes a statorarranged in housing. Statorincludes a stator corehaving a first axial endand a second axial endthat is opposite first axial end. Stator coreis coupled to inner surfaceof housing. Statorincludes a first end turnand a second end turn. In a non-limiting example, coolant inletand coolant outletare radially aligned and arranged axially inwardly of each axial end,of stator.

In accordance with a non-limiting example, statoris formed from a plurality of stator laminationshaving an outer diameteras will be detailed more fully herein. Stator laminationsare arranged in a plurality of lamination groups including a first lamination groupand a second lamination group. The number of lamination groups may vary. Second lamination group is circumferentially off-set relative to first lamination group. In an embodiment, second lamination groupmay be circumferentially off-set from first lamination groupby about 30°.

In a non-limiting example, first lamination groupis formed from a first plurality of laminationsspaced one, from another by a corresponding one of a first plurality of channels. Similarly, second lamination groupis formed from a plurality of laminations such as shown atspaced one from another by a corresponding one of a second plurality of channels. First and second pluralities of channelsandform part of a coolant flow path (not separately labeled) that extends circumferentially about plurality of laminations.

In a non-limiting example plurality of laminationsis formed by stacking and interleaving the first plurality of laminationsof first lamination groupwith corresponding ones of the second plurality of laminationsforming second lamination group. In a non-limiting example, each of the second plurality of laminationsis circumferentially offset from corresponding ones of the first plurality of laminationsforming first lamination group. The circumferential offset creates the first and second pluralities of channelsand. Each of the first plurality of channelsis axially and circumferentially offset relative to corresponding ones of each of the second plurality of channels. In a non-limiting example, inner surfaceof housingdefines an outer boundary of the first and second pluralities of channelsandand thus forms a surface of the coolant flow path. Reference will now follow toin describing one of the first plurality of stator laminationthat may form part of first lamination group. Stator laminationincludes a bodyhaving an inner surface sectionand an outer surface section. Inner surface sectionsupports a plurality of radially inwardly projecting stator teeth. In accordance with an exemplary embodiment, outer surface sectionsupports a plurality of cooling channel defining members, one of which is indicated at. At this point, it should be understood that each of the second plurality of laminationsincludes a second plurality of cooling channel defining members such as shown atin. Further, it should be understood that the first plurality of laminationsand the second plurality of laminationsmay be similarly formed.

In an embodiment, each cooling channel defining memberis radially off-set from an adjacent cooling channel defining memberby about 30°. It should be understood that the number of cooling channel defining membersmay vary as may the off-set between adjacent cooling channel defining members. Further, the offset may be different from or may be substantially the same as the off-set between adjacent lamination groups.

In accordance with an exemplary embodiment, each cooling channel defining memberincludes a first circumferentially extending portionand a second circumferentially extending portion. First circumferentially extending portionis spaced from second circumferentially extending portionby a gap. First circumferentially extending portionis also spaced from outer surface sectionto establish a first cooling channel portionand second circumferentially extending portionis spaced from outer surface sectionto establish a second cooling channel portion.

Each of the first plurality of stator laminationincludes an openingformed in each of the plurality of cooling channel defining membersand a partial openingformed in third cooling channel portion. First and second lamination groupandmay be offset relative to one another and joined as shown in. In an embodiment, each circumferentially extending portion,may include a recess or notch (not separately labeled) on an outer surface portion (also not separately labeled). The recess forms a bonding element receiving zone that may aid in joining statorto inner surfaceof housing. At this point, it should be understood that each of the second plurality of stator laminationsare similarly formed.

In an embodiment, a number of the first plurality of stator laminations, for example six (6) stator laminations, may be joined to form first lamination group. Similarly, a number of the second plurality of stator laminations, for example six (6) stator laminations, may be joined to form second lamination groupthat is circumferentially offset relative to and combined with first lamination group. That is, each laminationmay be interleaved with each laminationwhen lamination groupsandare formed. Additional lamination groups may be formed and joined together, each offset relative to another to form statorsuch as shown in. At this point, it should be understood that the number of laminations in a lamination group may vary. Further, while channelsandare shown as having a thickness of a single lamination, the thickness of each channelsandmay vary by adjusting how many laminations are combined prior to being interleaved.

In a non-limiting example, when first lamination groupand second lamination groupare combined, a split coolant path is formed as shown in. That is, coolant, such as oil, entering coolant inlet() passes into channelsandand flows circumferentially about stator core. The coolant passes axially through coolant passages defined by first and second cooling channel portionsand, passes through first plurality and second plurality of channelsandand enters into coolant outlet. Dividing coolant flow into channelsandvia first and second cooling channel portionsandreduces a pressure drop of the coolant and thus enhances stator cooling efficiency.

In a non-limiting example, a portion of the coolant entering coolant inletflows counter-clockwise through channelsuntil reaching cooling channel portion. The coolant flows into cooling channel portionin both axial directions. A portion of the coolant may pass from cooling channel portionand flow counter-clockwise into channels. A second portion of the coolant flow may pass axially out the channeland onto stator end turnsand/or. Additional coolant may pass into channelsand then into cooling channel portion. The second portion of the coolant may flow through cooling channel portionin channelin both axial directions. A third portion of the coolant may flow into an adjacent one of channelsand or may flow axially outwardly onto stator end turnand/or. The pattern repeats itself counter-clockwise until all the coolant is expelled axially from cooling channel portionsand.

In a non-limiting example shown in, a first end ringand a second end ringmay be installed on opposing sides of stator core. First and second end ringsandmay be connected through a plurality of mechanical fasteners, one of which is indicated atthat extend through corresponding ones of openingsand partial openingsin first and second groups of laminationsandas shown in. As will be detailed herein, end ringsandcooperate with the coolant passages defined by first and second cooling channel portionsandto deliver coolant to first and second end turnsandof stator

In a non-limiting example shown in, end ringincludes a plurality of openings, one of which is shown atthat are receptive of corresponding ones of the plurality of mechanical fasteners. End ringincludes an inner surfacethat abuts one of the plurality of laminations. In a non-limiting example, inner surfaceincludes a plurality of locator elementsthat orient end ringto stator core. That is, locator elementsestablish a selected circumferentially alignment of end ringrelative to stator core.

In a non-limiting example, inner surfaceof end ringincludes a plurality of coolant spray notchesthat align with one of channelsandand or the coolant passages defined by first and second cooling channel portionsand. The coolant spray notchesguide coolant onto end turnas shown in. In this manner, not only does the coolant reduce operating temperatures of stator corebut also lowers stator end turn temperatures. It should be understood that while the coolant spray notches are described as being on inner surfaceof end ring, additional coolant notches (not shown) are provided on end ring.

In accordance with a non-limiting example shown in, coolantenters coolant inletand a substantially bifurcates into a first coolant flow portionand a second coolant flow portion. First coolant flow portionenters coolant flow pathand flows circumferentially clockwise around the statorwithin first and second pluralities of channelsand. Second coolant flow portionflows circumferentially counter-clockwise about statorwithin first and second pluralities of channelsand.

Upon reaching channelsand, a portion of first and second coolant flowsandflows axially across stator. At this point, coolantexits channelsandat each of first axial endand second axial endand is sprayed onto corresponding ones of first and second end turnsand. The coolant continues to flow around and through first and second end turnsandand drops down to the bottom (not separately labeled) of housing. Coolantcollects at the bottom of housingand drains through coolant outlet.

In one non-limiting example, illustrated incoolant inletis located axially inwardly of first and second axial endand. Coolant outletis disposed axially outwardly of first and second axial endsand. In addition, electric motorincludes a rotor (not shown) having a hollow rotor shaft (also not shown) that may carry coolant which is sprayed onto an inner diameter() stator.

At this point, it should be understood that the exemplary embodiments describe a stator that includes radially outwardly extending projections, each including circumferentially extending portions that create a tortuous or serpentine cooling channel. With this arrangement, additional surface area of the stator laminations is exposed to cooling fluid thereby enhancing heat shedding capacity. The heat shedding capacity may be increased by as much as 50% or greater compared to existing systems. Further, the increased surface area of the stator laminations provides increased flux carrying capacity of the stator that may increase performance by as much as 5%. Thus, not only does the present invention provide additional cooling but also increases an overall operational efficiency of the electric motor.

The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims.